I recall reading a sci-fi novel that was set on a desert planet where the main character was part of the technologically backwards inhabitants of the planet, however there were some (at least two, but possibly more) technologically advanced people that also lived on the planet as well, and were rulers who were treated by the people as gods or wizards or something like that.
The main character is a male non-tech-savvy inhabitant of the planet who starts living under the jurisdiction of one of these rulers, but during the story travels to the domain of a different one. He might have been a refugee, but I am not 100% sure on that part. He did travel with a group of other people, and he was the leader of the group as I recall. He also had a female love interest in the group with him.
When they arrived at the place where the other ruler lived, he saw that the landscaping included water features, and was impressed by that. He met with the other ruler, who told him about something called "Makers", which the ruler had created and which would inhabit his body and help it to fight sicknesses, and to repair itself. The word "Makers" seems to have been the rulers way of dumbing down the concept so that it was able to be understood by the main character.
I am not sure if the "Makers" were genetically engineered biological creatures, or if they were nanobots of some sort, but whatever they were, they did infect him, and after a slight initial sickness he then felt their effects positively because he healed quicker from injuries.
Other than that, I can remember that there was a sandstorm at one point in the story during which they all had to hide in tents and wait it out. The book must have been published at least 20 years ago, since as I recall I read it after finding it in a library discard sale some time around 2010.