Will my data be erased if I install windows 11 from insider program

Installing Windows 11 Insider build is just like update and it will keep your data. However, since it is still beta and under testing , unexpected behavior are expected and like everyone said, it is good to take a backup of your data.
You may try File History, take a look at:
https://support.microsoft.com/en-us/windows/backup-and-restore-in-windows-10-352091d2-bb9d-3ea3-ed18-52ef2b88cbef