I've tried various things for people in my lane of travel whether pedestrian or other cyclist. I think the most effective I've done is just stop right where I am and let them move around me. So far it's been non-confrontational.
Of course you need to be aware of what's behind you or other traffic from elsewhere. I only do that when it's otherwise completely clear.
Works while I'm walking too for those that don't realize MUP guidelines here are "keep right, pass on left." Or for those that think their group has exclusive rights to the entire width of the trail.