Where can I get the white nylon inserts that are in the doors that are used to screw in to hold the door panels on. I replaced the outside window seals and most of the inserts are stripped so now the door handle bezel won't stay on and the door panel is loose.

 

I posted this recently concerning the armrest... It has the part numbers you need.
Just fix the same item on my 93 this weekend. I too orginally thought it was a plastic snap device, but isn't. I'll tell you my steps...
Before you pull your panel, I'd recommend the following. Order new anti rattle (Eckler 40932), You don't need to order the screws (Eckler 28766) because your old ones will work (and are better)...You also need screw retaining nuts (Eckler A9528), these are extremely expensive so just get them at Napa 665-2093. You'll beak about 4 of them since the plastic is old and brittle.
The top of your handle attaches to a plate, this plate is then connected to the door by a screw located under the electic window switch. Since your handle is missing the screw, this plate will fall off, so with a Sharpie marker, mark something on this plate so you'll remember which side face outside before you unscrew it.
To pull the panel you will see all the exposed screws except for 1 under the lock lever (just pry up on the front and it pops off), 1 under the door light (just pry on the top), and 1 under the window switch just pull the window switch out by prying on the sides,
So... There total screws there is about 5 on the bottom, 2 in the bottom of the door handle pull, 3 in the inside door latch (1 hidden under light, 1 hidden under lock lever, 1 you can see). 1 on the end on the door panel. Lastly, 1 under the electric window switch
Where you handle is broke, you'll be missing a screw. I believe the screw just gets loose and falls out. With the panel removed, just replace the screw that holds the top handle to the plate, which then attaches to the door.
The screw I used was Napa 665-1331 (for the handle). And Napa 665-1971 for the screw that dropped that I couldn't find.
Hope this make sense. Here's some picture too...

 

Your local NAPA dealer has a lot of bizzare plastic parts and oddball bolts/clips etc. They have a big book behind the counter with most of the stuff in it.