I've got a Price Pfister three handle/knob setup, very basic. I have replaced the seat on the hot side more times than I can remember, at least once every 8 or 9 months for the past several years. Sometimes the seat is eroded at the base, sometimes where the washer makes contact, makes no since to me. I generally use pipe dope on the threads and when I fix it, it's good to go for another 9 months of so. Why do I continue to have premature seat failure/erosion with this one, hot side valve? This last time I replaced the valve and seat both, with genuine Pf. It lasted a little longer, but still failed within a year's time, erosion at the base of Pf S70-500 Seat. I have attached a few examples from when I've had to replace the seat, I have many more, varying in where and how they eroded. I hate to have to replace the whole thing, when I may simply be missing something simple that is causing this. Any help is appreciated.