Need more information. Where are these cups? In your hubs? What make and model of bike?

In any case, if the cups are rusty and pitted where the bearings run on them, the part and bearings should be replaced. Cups are not usually chromed, except on cheap Ashtabula parts where they just chrome or nickel plate all of the working parts, including the cones. This usually flakes off from the pressure of the bearings and should be cleaned and re-greased after a few weeks use.

If you are referring to the outside part of a steel hub or something and its not a rare part, you may find it cheaper to locate a replacement in better condition, than to disassemble the wheel and have the hubs re-chromed. Otherwise, check your Yellow Pages for re-chroming businesses. They can tell you how to prepare the part before you give it to them. Make it clear that you do not want the interior (cups) chromed.