Almost any type of wood can be used if it is properly sealed to resist moisture.

Rosewood is a nice, dense, oily wood so it doesn't need much sealing etc. Burl woods like Claro Walnut are beautiful if they are reinforced (epoxy/fillers/liners, sometimes they are too brittle to be used on their own).

Look up "wood scales" or "knife scales" on the internet and you're bound to find more options than you ever wanted to choose between.