Had my scratch and dent floor model old Treager Lil Tex (I think that is the model) for ~ 8 years or likely more. The burn pot and the heat deflector/diffuser will rust over time. Period. High, direct heat with do that. Mine did. And while there are many Pellet Smokers that are of much higher quality than most Traegers (no offense to Traeger users, cause, well......I are one), the best thing about having a Traeger is replacement parts are abundant.
My burn post rusted out: I replaced it. My ignitor rod went out: I replaced it. My controller died: I replaced it. My heat deflector/difusser warped somewhat and rusted a bit: I did not replace it. Do not at this point see the need to replace that. I brush it off to removed the loose rust and keep an old, small, filthy shop vac handy to suck that up as well as ashes and from the burn pot and the rest of the chamber prior to a cook.
I cover the drip pan with heavy duty foil, most of the time. If I don't, I just scrap off the grease and creosote. The underside of the drip pan is treated like the heat diffuser: brush the loose rust dust and vac it out.
I never found the need to "cure" the inside of the cook chamber. I have a large and a small scraper, so I can get into a some of the nooks and crannies, but I am not obsessed about getting every bit of fat and creosotes out. I scrape of the grease and creosote off the chamber walls and vac that out too. If you use it enough, it self cures on the inside and that handles any other potential rust from developing.
I keep saying one day I may upgrade, but since my Traeger was never a high end one in the first place, I may have spent a total of $150 bucks in replacement parts.