Having studied hydraulics, water flow and pressure is a hydraulic situation. Pumps create flow and pipes create pressure. This is why homes are Piped 3/4 inch all the way to the area we want to plumb then reduce to 1/2 inch stubbed thru the wall and finally 3/8 to the fixtures .
Reducing down creates the necessary pressure needed at the fixture but larger piping to the general area will allow a high volume of water. Reduction in piping also prevents being roasted by hot water in the shower when someone flushes the toilet that got plumbed with 1/2 inch pipe. American mobile home manufacturers do this commonly (idiot syndrome to save pennies).
As for the well being 20 ft above the home, you would get that extra column of pressure created by gravity if you drilled straight down 20 ft then straight over to house, you may gain 20psi but since your coming down at an angle the column is not affected by gravity the same as a vertical column. I'm sure there's more math involved to find the advantage going down hill from the well. 1" or 4" you'll get the same results when they tie to the 3/4" piping at the house. Better off just running 1" right off the pump unless it's a submersed pump (1 1/4 to 2")then your dealing with head pressure and the pumps capability of pumping against gravity. I have heard that for solar purposes submersibles are a better alternative. They run off 220v and can keep up with those long showers.
For every foot of water column you achieve 1 psi, hence the popularity of water towers. Pumps keep the tank full much easier than pumps trying to keep up with varying customer demand.
Well, hope that clarifies it. Oz make my eyes crossed tho