Okay, California, over 100 deg, makes sense now. Might make sense to run 20-50 in the summer time, but I expect you'll be getting into the frigid 60's in a month or so, so IMO 10-40 is probably still the better choice. If however your oil pressure is low, you may be able to benefit from a thicker oil. Typically low oil pressure is caused by worn or loose bearings. Unless there were extenuating circumstances I wouldn't expect replacing the oil pump to improve this. Did replacing it improve your oil pressure?
If there's a question of oil pressure, I would install an aftermarket oil pressure gauge with numbers & get actual readings before switching oils and/or doing major work. Tim