Since jets use water from the body you are in to cool the motor, you are risking lots of rust and extra wear and tear to your parts with the salt, salt is abrasive and very corosive, so you will eventually run into problems, and the resale value will drop, however if your pump parts are stainless and painted/powdercoated well, it will be fine, but the motor, I don't know if there is anything you can do to make that prevent rust other than rinse it out very very well as soon as you get out of the water.