Are they carbon steel or stainless? As long as you handwash and towel dry them there shouldn't be a problem no matter what they are. Just don't let them drown in the sink or use the dishwasher if they're anything you want to keep looking nice.
Rusting under the scales is usually not a big problem, there may be some over time on an uncoated knife but nothing that would affect the function or even looks most of the time. If it's coated there's very little chance of it ever rusting under the tang.
If you have a bare steel tang you want to keep pristine and the slabs are removable you can either put a nice coating of good rust preventing oil like sheath or clp or something then reattach the scales, or if you don't mind a permanent installation you can use epoxy and then reattach the slabs. If you do this try to use 30 minute epoxy, the 5 minute can set pretty fast and it's also weaker.
As long as you handwash and towel dry them there shouldn't be a problem