nhMaster is right, the points in a starting relay are closed when the pump starts, they should not spark. They only spark after the pump starts, the starting amps are long gone, then they spark on opening. These points only close after the pump is off, when there is no power on the relay. Nothing wrong with having a larger starting relay but, this is only a bandaid for the symptom, not a cure for the problem. The main problem is the tank waterlogging, which can cause any relay to chatter like a telegraph machine, and burn up even the largest of points. The second problem is the wife and grandkids running a hose for extended periods of time.
Maintenance more often on the air and air charging system, or switching to a bladder type tank are the only ways to solve the waterlogging problem. The problem with the wife and grandkids using a hose, or not having the irrigation matched to the pump, can be solved by using a Cycle Stop Valve. These will stop the cycling as their name implies, because they vary the flow from the pump to match the hose, or whatever else is turned on. The starting realy taking such abuse is an indicator of how much abuse your pump is seeing. After replacing a realy a time or two, the motor is usually on it's last leg.
As upper so aptly put it, you have to have the right medicine. A bandaid is not going to cure an infection.