In LibreOffice Writer, you can set images to anchor "as character" (or other options) in order to set the pictures in-line with the text. This doesn't seem to be available in LibreOffice Impress. Is there another way of achieving this in Impress?
I believe there is a bug report already created for this feature in LibreOffice Impress. It was created last year and is still unresolved. It looks like this feature has not been impleented in Impress yet.
As far is a work around is concerned, I can't see any way to this at the moment. The person who filed the original bug report has his e-mail listed on that page, you may want to contact him to ask if he ever discovered a work around.