Water pump question

[SirNik84]

Inspecting my water pump last night and I think It might be the cause of the scum in my water system. the blades on the pump are made of steel and badly rusted. I replaced the water pump on my car about 4 years ago with one from NAPA and the vanes were made of brass!

I no longer have the water pump from napa do to an engine swap. I've been searching for a replacement water pump for my engine, but all I can find are pumps with steel blades. In a perfect world I'd go back to NAPA and order another pump with brass blades, but I don't have the budget for that. I have a line on a new pump but it has steel blades. I'm thinking of painting the blades before installing the steel pump, and maybe next summer when I give the car her citrus flush I will have the money to replace the pump.

Do you think painting the blades will work to keep the corrosion away? any special kind of paint? or any one know where i can get a cheap brass blade pump?