99% of oil pumps are 2 gears running together in a constant oil bath.
If the oil is kept clean and filtered, an oil pump should be good for 500,000 miles or so.

I recall seeing info on here about mounting an oil pressure sending unit using a 90 degree fitting on the front of the engine at an available port, however there was some concern about it's close location to the serpentine belt .
You could probably pipe the port up to the top of the engine and secure the sending unit out of harms way.