Sewing Tips for Hand-Sewn Hems and Inseams

A typical inseam pant stitch would be made with a serger (a tight looping stitch machine that also cuts to create perfect edge stitching - like what is probably already there) You can either try to mimic this stitch with tight looping stitches (over and under close together then add a straight "running" stitch over the middle of the flattened loops for double strength) or straight stitching in and out then supporting it along the inner side (the hem-side / cut-side) with a zig-zag stitch. Here is a diagram for better understanding.