Have you thought about using plasti-dip? Since the inserts sound like they are a pain to remove, you could do the following:
1. Remove the grille from the truck (to keep overspray off the rest of the truck)
2. Wash thoroughly with soap & water and let dry
3. Spray the grille and inserts with plasti-dip
4. Wait for the plasti-dip to dry (about 4 hours I think)
5. Use a sharp knife and cut the plasti-dip between the inserts and the grille surround
6. Peel the plasti-dip off the grille surround
7. Install the grille back on the truck
8. Enjoy your great looking grille!
I did basically the same to my truck (2013 Ram 1500), but I removed the inserts instead of the spray & trim technique I described above.