Should I replace JUST the fuel pump or the whole assembly, too? (P1605)

I have error code P1605 and had a mechanic test that my fuel pressure was lower than normal. He said it was because my fuel pump was getting clogged, which I believe considering my Tacoma was shipped from an island with presumably mid fuel quality.

My question is: do I need to buy just the DENSO fuel pump off RockAuto, or do I need to buy the whole assembly?

Open to other perspectives as I'll likely have a mechanic do this for me and would like to keep cost at a minimum.

Thank you TW!

Vehicle:

2014 Tacoma Single Cab 2.7L 4x4 (stock) 120k miles

 

If the fuel pump is the issue, just replace the pump.
Since you're in there, it would be best to install an external fuel filter. URD has a kit that replaced both.

 

This is the route I went, URD kit with the external filter means you don't have to drop the tank to replace a filter in the future. Kit comes with everything and the instructions are well done.

 

Thanks. That answers that!