That black trim is part of the fender flare, if I'm correct, or as the parts catalog refers to it, the "over fender, front-LH." It runs about $93+shipping from an online dealer, like CourtesyParts.com or NissanPartsDeal.com, not including any clips or hardware you may need. The other option would be to try locate one in a salvage yard, but you would likely have to purchase the whole, left fender. The part "may" also need to be painted.
Do a search on "welting" and you should see some threads talking about those strips. For the 2wds they are separate from the flare, I don't think the 4wd has anything similar. You may want to check your local dealer or call someplace like Courtesy.
I was going to try some generic product, but I was lucky, when I got around to dealing with mine it was all still there and intact. I had to use some weatherstrip adhesive to keep it in place but it is holding up well.