Any pump or a plumbing supply house that sells pumps should have any fitting you need, in a number of different materials. I've never seen the elbow at that link, and I would not use it if it were for my own use or a customer.
I would bring the PE up through the sanitary seal and use an insert by insert brass or SS 90 if you are burying it and sch 80 PVC if not unless it is out in the sun.
I see no need for a nipple going through the sanitary well seal, and I have never seen one used and I've worked on a fair number of single and dual hole sanitary well seals.
That nipple would require at least two threaded fittings plus the nipple and it would prevent anyone being able to loosen the seal in the future and pulling the PE up through it if possible while getting the seal out.