Three men met with Abraham, and Moses went out of his way for the next two chapters to call one of these men YHWH over and over again.
Are you talking about this verse:
The Lord appeared to Abraham near the large trees of Mamre. Abraham was sitting at the entrance to his tent. It was the hottest time of the day. 2 Abraham looked up and saw three men standing nearby. So he quickly left the entrance to his tent to greet them. He bowed low to the ground. (Genesis 18:1-2)
There's nothing in that passage that says God was among the three men. It's saying God appeared to Abraham (perhaps like the fire that Moses saw) and at the same time the three men (angels) showed up. God was not one among them.
Some might say that Abraham bowing low to the ground before the 3 men proves that God was among them. But Abraham was just honoring the angels, in the same way as Lot did.
The two angels arrived at Sodom in the evening. Lot was sitting near the gate of the city. When Lot saw the angels, he got up to greet them. He bowed down with his face to the ground. 2 “My lords,” he said, “please come to my house. You can wash your feet and spend the night there. Then you can go on your way early in the morning.” (Genesis 19:1-2)