I place some hives with homeowners on their property in suburban and semi-rural areas. I have an LLC which owns the hives, so got a business liability policy to cover my own side, incl. my yards and hives which are in transit. If someone hosting a hive for me (or their visitor) is injured, their homeowner's policy should cover it just like it would if they injury was caused by a different hazard on the site, like a swimming pool. I have a written contract with people who host my hives which lays all of this out.
If you are out in the country and placing hives on farmland you probably don't need to worry about this. If the landowner has an ag business, I think their business policy would cover instead of their homeowner's policy.
My homeowners insurance did not increase at all because of my beekeeping. I was careful to make sure my agent was fully aware of my beekeeping (and invited him out to see that it was safe and gave him some cut comb). Since he's an independent agent and also got me my business policy, it was win-win for him.
The take home:
If you are going to place hives on property you don't own, at a minimum you should have a written contract with the landowner which outlines all the terms of the agreement, including liability. It's worth it to have an attorney draft a contract template so you know it is in line with local laws.
If you're going to be doing this a lot, or in urban/suburban areas where more people will come in contact with the bees or you might run afoul of an HOA, consider getting a business liability policy to CYA. This may be a little over the top for those who don't need to form a business otherwise. If you don't have a business, your homeowner's should cover the liability on your own residential property, but won't cover the hives when they are elsewhere.