Repairing a ding or 3 might be practical using a filler. If there's a lot of rust and small pitting/bumping, like an old car bumper, this may not be practical. However, you could use something that will remove the rust, as rust grows (expands) and is quite abrasive. Then use a super-fine ceramic or even a very hard piece of polished steel (or even glass) to burnish down the high/rough spots before replacing seals.