1 hp equals roughly 750W of electrical power
the tricky part is the inrush current that will be for a pump application about 8X bigger than running current
you need an inverter from at least 1000 watt that is capable of suplying a power peak of 6000 watt for a short time (less than a second)
I warn you already NOT easy to find and NOT a bargain to buy
I would sugest to look for a 12 Volt pump motor and work with a battery set up charged with alternative power generation
Robert-Jan