I feel like I'm missing something, but maybe this is just a flaw in the software.
Whenever I draw diagrams in Pages, or insert images, they seem to just float there, and if I change text above, it causes the text to go past the image I inserted. For example, if I have a paragraph of text that references "the diagram below", and I add another paragraph above it, the diagram would now be above the paragraph of text because it doesn't move with the text as its editing.