And a few words from E.M. Forster about basing characters on people you know:
We all like to pretend we don’t use real people, but one does actually. I used some of my family... In no book have I got down more than the people I like, the person I think I am, and the people who irritate me. This puts me among the large body of authors who are not really novelists and have to get on as best they can with these three categories. We have not the power of observing the variety of life and describing it dispassionately. There are a few who have done this. Tolstoy was one, wasn’t he?
...A useful trick is to look back upon such a person with half-closed eyes, fully describing certain characteristics. I am left with about two-thirds of a human being and can get to work. A likeness isn’t aimed at, and couldn’t be obtained, because a man’s only himself amid the particular circumstances of his life and not amid other circumstances... When all goes well, the original material soon disappears, and a character who belongs to the book and nowhere else emerges.