The ornamental design for a bun with insert, as shown and described.
FIG. 1 is a perspective view of a bun with insert;
FIG. 2 is an exploded, perspective view of the bun with insert of FIG. 1;
FIG. 3 is a top view of the bun with insert of FIG. 1;
FIG. 4 is a bottom view of the bun with insert of FIG. 1;
FIG. 5 is a side view of the bun with insert of FIG. 1, with the opposite side view, the front view, and the rear view being identical images thereof;
FIG. 6 is a cross-sectional, side view of the bun with insert of FIG. 1 taken along line A-A of FIG. 3;
FIG. 7 is an exploded, side view of the bun with insert of FIG. 2; and,
FIG. 8 is an exploded, cross-sectional, side view of the bun with insert of FIG. 1 taken along line A-A of FIG. 3.
Evenly spaced broken lines of FIGS. 1-8 illustrate portions of the bun with insert that form no part of the claimed design. The dash-dot-dash broken lines in FIGS. 1-3 and 6-8 illustrate the boundary of the claimed design which forms no part thereof.