That looks more like calcereous build up rather than corrosion as the "bumps" stand proud of the surface.
Most propellers are "manganese bronze" which is misleading as mb is actually a brass due to it's high zinc content. Manganese bronzes typically show corrosion with pits and a pinkish hue due to dezincification.
PS. The jam nut in your photo is in the wrong place, it should be against the prop hub.
Aphorisms to live by .....
If you can live with the consequences, go for it - wg
Y'am what I y'am an' thats' all that y'am - Popeye