Syntax to display only the node body using node embed module
That should be only [[nid:1234]] without body in it, as it embeds body by default. Also, make sure you've enabled the filter at admin/config/content/formats/TEXT_FORMAT.
Edit: Adding my comment in here to make it more clear.
If you wish to only show body of a node within node, you can do so by:

Turning on the &quot;Node Embed&quot; view mode at admin &gt; structure &gt; types &gt; manage &gt; CONTENT_TYPE &gt; display


Changing the settings of the &quot;Node embed&quot; mode to only display body of the node. Node embed module uses this view mode by default (if enabled for a particular content type).

You will now be able to use the above syntax without any need to specify any options.


P.S. - You could use the Display Suite module to have a better control the display of the fields.