Drain pears, reserving syrup; reserve 1 pear half for topping. Process remaining pear halves in blender or food processor until smooth; transfer to 1 cup measure. Add as much of the reserved pear syrup as needed to make 1 cup. Reserve remaining syrup for other use.
Mix flour, sugar, baking powder, salt, and nutmeg in large bowl. Mix pear puree, oil, egg, and orange rind in medium bowl. Add to flour mixture; stir just until moistened. Fold in walnuts; batter will be stiff.
Spoon batter into greased 8 1/2 x 4 1/2 x 2 3/4 inch loaf pan. Cut reserved pear half into 6 slices; arrange crosswise in a row on top of batter. Bake in preheated 350 degrees until wooden pick inserted near center is withdrawn clean, 50-55 minutes. Cool pan on wire rack 5 minutes.
In small bowl, mix powdered sugar and as much of the orange juice as needed to make a thin, smooth glaze. Remove bread from pan; spoon glaze on top of bread. Cool completely on wire rack. Wrap bread in aluminum foil; let stand overnight before slicing.
