There isn't a simple way to display OLE objects (even simple ones such as
images) in a Word mailmerge. The only straightforward way to do it is to
export all the images you need to separate files, using some name that
associates them with the record they came from, then use an INCLUDEPICTURE
field to include them.

For example, if each record has a key called k with values 1,2,3 and all the
images are .jpgs you could export all the images to

c:\myimages\image1.jpg
c:\myimages\image2.jpg
c:\myimages\image3.jpg
etc.

then use a nested field such as

{ INCLUDEPICTURE "c:\\myimages\\image{ MERGEFIELD k }.jpg" }

where all the {} are the special field braces you can insert using ctrl-F9