John;

I agree with Ed; but will add that there should be some means of trapping water before the pump.  The pump can handle small particulates, but can disperse water which may allow some to get past a filter.  A fine filter upstream from the pump is a vapor lock hazard; particularly if you intend to run auto fuel.  You gascolator will serve as the water trap before the pump, but may also have a very fine screen, so it would be good check that frequently, particularly during initial operation.  Gascolators are adequate for carburetors, but for FI you’ll want some finer filter downstream from the pump; maybe 20 microns or so.

Al

I personally believe placing a high pressure filter after the pump is the preferred solution.  I use a coarse filter

(wire mesh) before the pump to keep any large foreign matter out of the pumps.  If your injectors clog it doesn't matter what kind of filter you have before the pump or how well the pump is protected.  Others will argue that a fine filter before the pump protects both - unless of course the pump starts to shed material.

One thing to consider is that a filter of any kind will cause a pressure drop, the finer it is (and therefore the more restrictive) the more of a pressure drop.  Pressure drops before the intake of a pump can lead to cavitation and formation of bubbles in the fuel line leading to "vapor lock".

In the auto, the screen inlet in the tank acts like a coarse filter ( before the pump) and the filter outside the tank is a finer filter.

There you have my 0.02 on the topic

Ed