the protege's have lots of rust problems, but i have not seen or heard of them in the newer mazda's. (2004+)
that being said, my 2008 5 has a lot of paint chips, but i drive a lot of interstate, and MI uses a lot of salt and sand. Not to mention, stupid gravel haulers. however, i havent noticed any rust. (i fix the chips and was well) i doubt your 2010 would rust that quick.