there are hot water heaters that are designed with mineral resistent elements.... that being said, one effective method on the water heaters is purchasing a two element water heater and using the top element in the water heater only, that way any mineral build up doesn't reach the top element. you can also daisy chain two waater heaters together using the first with only a top element as a fire wall so to speak. we have a softner set-up on our well, but feeding that device pellets is a never ending chore. i understand there are some better designed softners now that dont require salt or any other kind of pellets, we also tried an in-line filtration system
