A loud pump isn't a sign of impending failure, it's a sign that it isn't isolated properly.
Go to ChinaMart and pick up two or three cheap mouse pads, you'll also want between two and six feet of foam pipe insulation the kind you would normally use to prevent freezing except without the heat tape installed, get the stuff that's sized for 1/2" pipe which is probably what your rig has installed. Once you've got these little goodies climb into the cubby where your water pump is and unscrew it from the floor. While it's unscrewed take the pipe insulation and cover as much of the "outbound" water line from the pump that you can paying careful attention to anywhere it contacts the wall, cabinets or floor, use wire ties or electrical tape to secure the foam insulation so it stays put. After you've got that taken care of you can take your two or three mouse pads and set your water pump on them then screw it back to the floor. Don't yard down on the screws it's not going to go flying across the room on it's own, just lightly screw it down with the mouse pads under it so it doesn't wander off the pads.
The last step is to run at least five gallons of water through each of your faucets using the pump. If you've got air trapped somewhere it can really add to the racket when the pump is running. RV manufacturers aren't in the business of taking extra time to ensure that little things like water pumps are less annoying.
