You should compare geography with geography OR geometry with geometry.
And also you need to set the SRID.
 
So in your case you need

    WHERE ST_DWithin(geom::geography, ST_SetSRID(ST_MakePoint(79.3832,43.6532),4326)::geography, 50000);

OR

    WHERE ST_DWithin(geom::geography, ST_GeogFromText('SRID=4326;Point(79.3832 43.6532)'), 50000);

Then, from your profile details, I bet the longitude must be **-79.3832**, because currently you're searching for cities around a place in southeastern Kasachstan with not much around, while you probably want to search cities around Toronto.

    WHERE ST_DWithin(geom::geography, ST_GeogFromText('SRID=4326;Point(-79.3832 43.6532)'), 50000);