A good many people from Hemingway's life found their way into his
fiction, which is highly autobiographical.
"A Farewell to Arms," for example, tells the story of a young American
volunteer who is wounded in Italy in World War One and is treated at a
hospital where he meets a British nurse, Catherine Barkley. They fall
in love, but Catherine is later killed in the war.
The novel is based on Hemingway's own experiences. At the age of 19,
Hemingway volunteered as an ambulance driver in Italy (before America
entered the war). Injured by an Austrian mortar shell, he recovered at
a hospital where he fell in love with a spirited American Red Cross
Nurse several years older than he, Agnes Von Kurowsky.
After Hemingway returned to the United States, they corresponded. But
he was bitterly disappointed when Agnes wrote a letter stating her
belief that her greater age was a barrier to a relationship.
The passionate (and doomed) love affair between Lt. Henry and
Catherine in the novel can be seen, therefore, as a romanticized
version of Hemingway's relationship with Agnes, who seems not to have
returned his feelings in kind.
Probably the best known example of Hemingway's penchant for basing his
fictional characters on people he knew is "The Sun Also Rises." The
novel was inspired by a trip he took in 1925 with his first wife,
Hadley Richardson, to the Pamplona fiesta and running of the bulls in
Spain. The novel is perhaps the most famous fictional portrayal of the
1920s American expatriate community in Paris, of which Hemingway was a
Lady Brett, the principal female character in the novel, is based on
the British aristocrat Lady Duff Twysden, a member of the Hemingway
circle at Pamplona. During the fiesta, Hemingway introduced Twysden to
the bullfighter Cayetano Ordonez, the inspiration for the novel's
bullfighter, Romero. The same kind of introduction happens in the
novel. Jake, the novel's protagonist and a writer, introduces the
promiscuous Lady Brett to Romero, with unfortunate results. Like his
fictional alter ego Jake, Hemingway seems to have felt guilty
afterwards for having caused the noble bullfighter to be distracted by
Other characters in the novel had their real life counterparts. The
character of Cohn seems to have been based on Harry Loeb, a
fellow-expatriate in Paris. (See: "A Moveable Feast," Hemingway's
memoir of his Paris years). The character of Mike is the fictional
equivalent of Pat Guthrie, Lady Tywsden's fiancee. And Jake's friend
Bill Gorton derives from Hemingway's real life friend, Ogden Stewart.
This is by no means an exhaustive answer to your question (that would
require a book!), but I hope that it helps.