1993 GMC Sonoma OIL PUMP

Well, they make a special tool for that. BUT, I always used an open end wrench the size of the pickup tube, if I remember correctly 11/16, and with the pump in a vise lube the end of the pickup. Start the tube in the pump trying to get the bottom of the tube(screen end) square with the bottom of the pan and using the wrench as a "spanner" tap the tube into the pump housing with a hammer.
If you tap the pickup 1/2 way in you can mount the pump in the block then either "eyeball" the pump being square with the bottom of the block, OR, hold the oil pan to make sure it doesn't rock on the screen. If you have to adjust the screen a little you can then drive the tube in the rest of the way. Hope this helps.